PORT MORESBY, Papua New Guinea - An outbreak of typhoid fever has struck refugees detained by Australia on Papua New Guinea's Manus Island.

General secretary of the Catholic Bishops Conference of PNG Giorgio Licini said two men diagnosed with the potentially fatal disease were flown to Port Moresby this week for treatment.

"It has been established that it is typhoid fever. That's why they were moved fast," he said.

Suspected cases of the illness are affecting other men in all three refugee detention centres on the island, where Father Licini is visiting over Easter.

Sri Lankan refugee Shaminda Kanapathi said the two men from Bangladesh and Pakistan were diagnosed at the island's Lorengau hospital.

Staff immediately cleaned the men's rooms at West House and Hillside House to avoid contagion, he said.

Typhoid Fever is contracted through contaminated food or water.

Fr Licini said food given to the men in the three camps was prepared in different kitchens but all were supplied with water from the same river.

"I personally suspect this has come from water. Not the drinking water which is separate but shower water," he said.

A letter referring a refugee with suspected typhoid fever to the hospital was witnessed by Fr Licini.

"But he was told in the Lorengau provincial hospital that they had run out of the equipment necessary to do the test so he was sent back to his place," he said. "It may not be out of control but... if it is a larger problem of contaminated water it is better to take things seriously. Typhoid fever is not something to be underestimated," the priest said.

"I had it myself years ago. I remember the symptoms and treatment had to be punctual and fast and in hospital."

The men's symptoms included a high fever and headache, with body and joint pains, vomiting and bloody diarrhoea, Mr Kanapathi said.

He estimated between 15 and 20 men were symptomatic.

"Keeping men confined in camps lacking basic hygiene… can easily lead to this situation," he said.

The Australian government issued a statement on Good Friday to news agency AAP.

"This is a matter for the government of Papua New Guinea," a spokesperson from the home affairs department said.

The department said it provided funding to help the PNG government provide "offshore health services."

The sick refugees are among about 500 men in detention on Manus since 2013.

In 2017, the Australian government reached a $US50 million settlement with about 2,000 men claiming false imprisonment on Manus, in conditions that caused serious physical and psychological injuries.

Seven refugees have died in detention on the island, including Hamid Kehazaei, who succumbed to sepsis in 2016, and Reza Barati, who was murdered by security staff during a riot in 2014.

While marking his 6th Easter on Manus, Mr Kanapathi recalled the Good Friday attack of 2017.

PNG defence force personnel fired more than 100 rounds into the former detention centre on the island's Lombrum naval base, following a dispute with refugees.

"Having survived... we realised that again we were just lucky enough to be alive. We fled our family and home country to escape being tortured, persecuted and eventually killed but here we were experiencing the same treatment," Mr Kanapathi said.

"On this Easter Good Friday, I'm calling the Australian people to call their politicians to account for the ongoing violence against us and bring an end to this devastating policy enacted in your name."

(The writer Benjamin Robinson-Drawbridge is a journalist covering the Pacific for Radio New Zealand).